GB1593105A

GB1593105A - Stabilization of polyphosphazenes

Info

Publication number: GB1593105A
Application number: GB10511/78A
Authority: GB
Original assignee: Firestone Tire and Rubber Co
Current assignee: Bridgestone Firestone Inc
Priority date: 1977-03-21
Filing date: 1978-03-16
Publication date: 1981-07-15
Also published as: JPS5426587B2; IT1113065B; AU520390B2; CA1098281A; AU3414478A; US4101507A; FR2384823B1; IT7821355A0; DE2811525A1; FR2384823A1; JPS53146758A; NL7803041A; BE864843A; DE2811525C2

Description

PATENT SPECIFICATION ( 11) 1 593 105

lj, ( 21) Application No 10511/78 ( 22) Filed 16 March 1978 0 ( 31) Convention Application No 779390 ( 32) Filed 21 March 1977 in CO ( 33) United States of America (US) o ( 44) Complete Specification published 15 July 1981 ( 51) INT CL 3 C 08 K 5/34 _ 1 ( 52) Index at acceptance C 3 K 124 127 210 241 262 270 290 CB C 3 W 330 ( 54) STABILIZATION OF POLYPHOSPHAZENES ( 71) We, THE FIRESTONE TIRE & RUBBER COMPANY, a Corporation organized under the laws of the State of Ohio, United States of America, of 1200 Firestone Parkway, Akron 44317, State of Ohio, United States of America, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly 5

described in and by the following statement:-

This invention relates to the protection of polyphosphazene vulcanizates from thermal degradation when exposed to temperatures up to about 5000 F, in various environments such as those which may be encountered in service at elevated temperatures More particularly, it relates to the incorporation of a synergistically 10 active combination of additives in such polyphosphazenes to inhibit thermal degradation of the same.

Because of an attractive combination of physical and chemical properties considerable attention has recently been given to polyphosphazenes which have been described in a number of recent scientific articles and in the following United 15 States Patents, among others:

Inventor Patent No Issued Allcock et al 3,370,020 February 20, 1968 Rose 3,515,688 June 2, 1970 Reynard et al 3,700,629 October 24, 1972 20 Rose et al 3,702,833 November 14, 1972 Reynard et al 3,853,794 December 10, 1974 Reynard et al 3,856,712 December 24, 1974 Rose et al 3,856,713 December 24, 1974 Reynard et al 3,883,451 May 13, 1975 25 Cheng et al 3,972,841 August 3, 1976 In the present specification the term polyphosphazene is intended to include the polymers described in the above noted patents and other similar materials represented by the general formula -P-N 30 in W c ae psin in which each X is a monovalent group e g alkoxy, substituted alkoxy including fluoroalkoxy, aryloxy, substituted aryloxy, amino, and other such groups and the several X groups may all be the same or they may differ and N is an integer greater than 3 and preferably between 20 and 50,000 Some of the X groups may include some unsaturation, e g as described in Cheng et al United States Patent 3, 972,841 35 issued August 3, 1976.

Previous efforts to inhibit the thermal degradation of such polyphosphazenes have been directed to the incorporation therein of basic metal oxides or similar compounds or of metal dithiocarbamates Metal oxides are insoluble in these polymers and hence have a relatively low level of activity Metal dithiocarbamates are partially soluble in these polymers, but are limited in use by the fact that they promote crosslinking (gelation) on extended aging and they are incompatible with 5 peroxide curatives The use of metal dithiocarbamates is described and claimed in United States Patent 3,843,596 issued October 24, 1974, which also describes and claims the use of basic inorganic compounds of alkali and alkaline earth metals.

Another prior art suggestion for stabilizing polyphosphazenes against thermal degradation is set forth in United States Patent 3,867,341 issued February 18, 1975 10 to G S Kyker.

Still another system for stabilizing polyphosphazenes is described in United States Patent No 4,017,458 which describes the use of the zinc salt of 2mercaptobenzothiazole for this purpose.

Some of these and some of the other stabilizers reported in the literature tend 15 to impart an undesirable color, (yellow turning to brown) to the polymer, especially on prolonged exposure to sunlight.

A principal object of this invention is the protection of polyphosphazenes from thermal degradation by the addition of a combination of stabilizers which appear to act synergistically 20 A further object of the invention is to stabilize polyphosphazenes against thermal degradation by means of a combination of additives which do not adversely affect vulcanization (curing) of the polymers or their physical properties, and which does not impart any noticeable color to their vulcanizates.

A further object of the invention is to provide a stabilizer which can be added 25 to the polymer in any of the usual mixing apparatus such as mill, Brabender, or Banbury mixing or kneading, without special procedures.

These and other objects of the invention will become apparent from the description of preferred embodiments of the invention which are intended to illustrate the same and are not intended to limit the invention in any way 30 The present invention provides a poly(phosphazene) composition stabilized against thermal aging comprising ( 1) a poly(phosphazene) represented by the general formula:

X N p x 1 n wherein N represents an integer from 20 up to about 50,000 and X and X, each 35 represent alkoxy, substituted alkoxy, aryloxy, substituted aryloxy, hydroxy, or amino, and X and X, are randomly distributed along the -P=N backbone, and ( 2) a stabilizer consisting of an organic compound compatible with said poly(phosphazene) and present in an amount sufficient to stabilize said poly(phosphazene) against thermal degradation, said organic compound being 40 selected from hydroxy or mercapto picolinamide and hydroxy or mercaptothiopicolinamide optionally further containing one or more substituent groups selected from alkyl, aryl, alkoxy, halogen hydroxy and mercapto groups, and an amount of a basic oxide sufficient to render said picolinamide effective as a stabilizer 45 Preferably, X and X, in the formula above are fluoroalkoxy or fluoroaryloxy groups More particularly, the X groups are preferably OCH 2 CF 3 and the X 1 groups are mixtures of OCH 2 (CF 2),CF 2 H and OC 6 H 4 CH 2 CH=CH 2 in which y is either 1, 3, 5, 7 or 9 in which case the ratio of X to X, is preferably from 95 to 5 and 50 to 50 and the composition preferably additionally contains from 0 2 to 5 0 mol ,? 50 o-allylphenoxy groups.

Preferably the picolinamide or thiopicolinamide is present in an amount of from 0 05 and 50 Y by weight.

The invention also includes elastomers, plastics, thermoplastic elastomers, fibers and vulcanized articles consisting essentially of the stabilized 55 polyphosphazene compositions.

1,593,105 The invention also includes peroxide cured polyphosphazene compositions as above in which from 0 2 to 5 0 % of the groups X or X 1 are unsaturated.

In the examples which follow 100 parts by weight of polyphosphazene polymer of the general formula OCH 2 CF 3 -NP OR n wherein OR' equals OCH 2 (CF 2)m CF 2 H; m equals 1, 3, 5, 7, 9 and in which N is about 20 to 50,000 or more and all of the other additives except the peroxide curing agent were mixed for ten minutes in a Brabender mixer The master batch was cooled to ambient temperature and added to a 55 C mill and the peroxide curing agent was then added to the mill After milling for a sufficient time to insure complete distribution of the curing agent, the batch was molded into slabs 6 "x 6 "x O 5 " which were then cured for thirty minutes at about 171 C Test rings were cut from the cured slabs and aged 240 hours at 175 C Physical properties of the aged rings were then compared to the unaged controls Different levels of the stabilizer, 3-hydroxypicolinamide were compounded with the following composition:

Material Polymer Silica (Quso WR 82; Quoso is a registered Trade Mark) Magnesium Oxide Peroxide (Vulcup 40 KE; Vulcup is a registered Trade Mark) Stabilizer Parts 1.25 as in Table

Examples 1-9 show the effect of different levels of 3-hydroxypicolinamide with a uniform level of Mg O.

Quso WR 82 is a precipitated silica containing a proprietary siloxane coating and is obtained from Philadelphia Quartz, Inc.

Vulcup 40 KE is a 40/60 mixture of a,a'-bis(t-butylperoxy) diisopropylbenzene on Burgess clay; both para and meta isomers are present in unspecified ratios; the material is obtained from Hercules, Inc.

Stabilizer, phr Modulus @ 100 O Elongation, M Pa unaged 240 Hrs @ 175 C Retention, O Tensile Strength, M Pa Unaged 240 Hrs @ 175 C Retention, TABLE I

1 2 3 4 5 6 7 8 9 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 6.9 8 0 7 9 7 2 7 5 7 8 7 0 7 7 7 4 2.7 3 5 4 3 5 5 5 5 5 6 5 6 5 9 5 6 39 44 54 76 73 72 80 77 76 9.8 10 1 9 9 7 5 8 3 8 4 8 3 8 3 8 4 5.4 5 7 6 6 6 2 6 8 5 9 6 0 6 2 5 9 56 67 83 82 70 72 75 70 In the above table the M Pa values can be converted to pounds per square inch by dividing the M Pa value of 0 006895.

The nature of the filler and the amount of filler is not critical and instead of a silica filler as in the Examples, a carbon black filler may be used.

The amounts of Mg O which are effective in combination with the picolinamide vary from about equal parts by weight to as much as 20 times as much Mg O as picolinamide by weight A range of about I to 20 parts of Mg O per 100 parts of polyphosphazene has been found effective with 3-10 parts per 100 parts of polymer being preferred.

In addition to 3-hydroxypicolinamide, other picolinamides with alkyl, aryl, S 1,593,105 alkoxy or halogen substituents on the pyridine ring in the 4, 5 or 6 positions, and other 3-substituted picolinamides, especially 3-hydroxythiopicolinriamide and 3mercapto thiopicolinamide exhibit the same synergism with Mg O.

Corresponding amounts of Zn O have been found to behave in much the same manner as Mg O and may' be substituted for the Mg O without departing from the intended scope of the invention.

In the absence of either Mg O (or Zn O) the picolinamides are not effective as stabilizers in cured polyphosphazene, as is apparent from the data below.

TABLE II

Evaluation of 5-Hydroxypicolinamide in the A B Polymer (PNF-200 R) 100 0 100 0 Silica 36 0 36 0 Mg O 0 0 0 0 3-Hydroxypicolinamide 0 0 0 5 Peroxide (Vulcup 40 KE) 1 25 1 25 Modulus @ 100 % Elongation, Unaged 240 Hrs @ 175 C Retention % Tensile Strength, M Pa Unaged 240 Hrs @ 175 C Retention O M Pa 7.3 4.6 8.3 7.1 5.7 3.3 9.0 6.4 Absence of Magnesium C D 0 100 0 36.0 36 0 0.0 0 0 1.0 1 5 1.25 1 25 6.5 3.6 9.1 6.7 6.6 3.4 9.5 6.3 While not wishing to be bound as to how the Mg O and picolinamide cooperate in stabilizing the polymer, it has been found that stabilization is also achieved by the use of the magnesium compound of the picolinamide, and such is a preferred stabilizer in the present invention.

The magnesium bis( 3-oxypicolinamide) is prepared as follows:

OH C-NH 2 II 011 0 o + Mg Ct 2 6 H 20 +Na OHCNH 2 11 II -Mg +Ns CO +H 20 One-tenth mole ( 13 8 g) of 3-hydroxypicolinamide was dissolved in 300 ml water containing 4 8 g ( 0 11 mole) of sodium hydroxide to give a pale yellow solution A solution of magnesium chloride hexahydrate ( 11 2 g, 0 055 mole, in 100 ml water) was added dropwise at ambient temperature to the above solution causing a white precipitate to form When the addition was complete, the precipitate was collected by filtration, washed several times with water to remove occluded sodium chloride then dried under vacuum The product weighed 16 5 g ( 99 %) and contained two molecules of water of hydration The structure was confirmed by elemental and mass spectral analyses The product became a bright yellow above 300 C and underwent a reduction in volume above 330 C but did not melt below 370 C.

Polyphosphazene polymer was mixed, molded and tested as in the preceding examples except that the stabilizer was the magnesium picolinamide The results were as shown in the following table.

Oxide E 0 36.0 0.0 2.0 1.25 5.4 2.8 8.0 5.8 1,593,105 TABLE III

Evaluation of Magnesium Bis( 3-oxypicolinamide) in Polyfluorophosphazene Vulcanizate A B C D E Polymer (PNF-200 R) 100 0 100 0 100 0 100 0 100 0 5 Silica (Quso WR 82) 30 0 30 0 30 0 30 0 30 0 Mg O 6 0 6 0 6 0 6 0 6 0 Vulcup 40 KE 1 15 1 15 1 15 1 15 1 15 Stabilizer 1 0 2 0 3 0 4 0 Modulus @ 100 Elongation, M Pa 10 Unaged 7 3 6 8 6 6 6 7 6 3 240 Hrs @ 175 C 4 0 4 5 5 9 6 5 7 1 Retention O 54 66 89 97 113 Tensile Strength, M Pa Unaged 9 2 8 4 7 9 7 8 8 3 15 240 Hrs @ 175 C 6 8 7 5 8 7 8 1 8 0 Retention o 74 89 110 104 96 The mixing, molding and test conditions were identical to those described in the disclosure.

In the preceding examples, the polyphosphazene utilized in the formulation 20 was one in which the substituent groups were trifluoroethoxy (-OCH 2 CF 3) and telomer fluoroalkoxy l-OCH 2 (CF 2)m-CF 2 Hl as described in Rose U S Patent No 3,515,688, the ratio between the two being about 70/30 on a mol %? basis The polymer contained phosphazenes with N from 20 to 50,000, the molecular weight distribution being similar to that described in Table III of a Paper published in the 25 Journal of Polymer Science Vol 14 pages 1379-1395 ( 1976) by D W Carlson et al.

Claims

WHAT WE CLAIM IS:-

1 A poly(phosphazene) composition stabilized against thermal aging comprising ( 1) a poly(phosphazene) represented by the general formula:

x N P\ 30 XI n wherein N represents an integer from 20 up to about 50,000 and X and X, each represent alkoxy, substituted alkoxy, aryloxy, substituted aryloxy, hydroxy, or amino, and X and X, are randomly distributed along the -P=N backbone, and ( 2) a stabilizer consisting of an organic compound compatible with said poly(phosphazene) and present in an amount sufficient to stabilize said 35 poly(phosphazene) against thermal degradation, said organic compound being selected from hydroxy or mercapto picolinamide and hydroxy or mercaptothiopicolinamide optionally further containing one or more substituent groups selected from alkyl, aryl, alkoxy, halogen, hydroxy and mercapto groups, and an amount of a basic oxide sufficient to render said picolinamide effective as a 40 stabilizer.

2 A composition according to claim 1, wherein the picolinamide or thiopicolinamide is present in an amount of from 0 05 and 5 O o by weight.

3 The stabilized poly(phosphazene) composition of claim 1 or claim 2 wherein X and X, are fluoroalkoxy or fluoroaryloxy groups 45

4 The composition of any one of claims I to 3, wherein the basic oxide is Mg O.

The composition of any one of claims I to 4, wherein the picolinamide is substituted with hydroxy, alkyl, aryl, alkoxy or halogen.

6 The composition of claim 4 with between 1 and 20 times as much Mg O as 50 picolinamide by weight and the amount of Mg O is in the range between I and 20 parts per hundred parts by weight of said polyphosphazene.

1,593,105

7 The composition of any one of claims I to 6, wherein the picolinamide is 3hydroxypicolinamide.

8 The composition of any one of claims I to 7, wherein the stabilizer is magnesium bis( 3-oxypicolinamide).

9 Elastomers consisting essentially of the stabilized polyphosphazene 5 composition of any one of claims I to 8.

Plastics consisting essentially of the stabilized polyphosphazene composition of any one of claims I to 8.

11 Thermoplastic elastomers consisting essentially of the stabilized polyphosphazene composition of any one of claims I to 8 10

12 Fibers consisting essentially of the stabilized polyphosphazene composition of any one of claims I to 8.

13 Vulcanized articles consisting essentially of the stabilized polyphosphazene composition of any one of claims I to 8.

14 Peroxide cured polyphosphazene compositions of any one of claims I to 8

15 in which from 0 2 to 5 0 percent of the groups X or X, are unsaturated.

The compositions of claim 14 in which the groups X are OCH 2 CF, and the groups X, are mixtures of OCH 2 (CF 2)y CF 2 H and OC 6 H 4 CH 2 CH=CH 2 in which y is either 1, 3, 5, 7 or 9, and mixtures thereof.

16 The composition of claim 15 in which the ratio of X to X, is from 95 to 5 20 and 50 to 50 and which contains in addition from 0 2 to 5 0 mol oallylphenoxy groups.

STEVENS, HEWLETT & PERKINS, Chartered Patent Agents, Quality Court, Chancery Lane, London, WC 2 A IHZ.

Printed for Her Majesty's Stationery Office, by the Courier Press, Leamington Spa, 1981 Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

1,593,105